1. Technical Field of the Invention
The present invention relates to a tool for machining viscoelastic products; more precisely, it relates to a cylindrical cutting tool for a machine for detreading and machining rubber products such as tires.
2. The Related Art
Tires are known to comprise a tread consisting of an outer layer of rubber-based mixtures, of greater or lesser thickness, in which are molded various grooves and tread patterns intended, inter alia, to improve the vehicle's grip relative to the ground.
In certain cases, it is necessary to machine the outer surface of the tire: for example, to prepare for retreading of a worn tire or, indeed, to obtain a “worn” tire from a new tire, with a view to performing certain tests on the rigid belt, or on the carcass, without being hampered by the very considerable heating associated with the thickness of the rubber of the new tread during the tests.
In the first case (retreading), tires are machined by abrasion (see for example International Publication No. WO 00/15388), but this process causes superficial heating which it is sometimes desirable to avoid. Moreover, a good surface state is sometimes required; a cutting process is then used. In general, the tire is made to turn about its axis and is moved towards the tool by translational movement of part of the frame (see for example U.S. Pat. No. 4,036,275).
The cutting tools used are generally cylindrical, that is to say, the cutting edge of the blade is circular, and they are rotationally mobile about their axes in order to improve cutting (see for example U.S. Pat. No. 3,426,828). The cut material passes inside the cylindrical tool and is discharged in the form of a strip of greater or lesser length depending on the tread pattern of the tire. In the case of a heavy goods vehicle tire, with longitudinal ribs, the length of the strip may reach several meters and even exceed meters, which poses discharge problems and may also cause jams.